Automatic enabling/disabling of termination impedance for a computer bus

Abstract

A system and method for automatically enabling and disabling a termination impedance circuit for a computer bus. A peripheral device on the computer bus has two external bus connectors. A connector cover is provided for at least one of the peripheral bus connectors. The connector cover must be removed before a mating bus cable connector can be attached. The presence or absence of the connector cover is detected by sensor within the peripheral device. If a connector cover is detected, one of the peripheral bus connectors must be open (not connected to the bus) and termination is enabled. If a connector cover is not detected, termination is disabled. In one embodiment, the connector cover has a projection that passes into the peripheral device. In an alternative embodiment, a reflective surface is used. The cover may optionally be captured by a hinged edge or attached via a tether.

What is claimed is: 
     
       1. An apparatus for controlling a termination impedance circuit in a device on a computer bus, the apparatus comprising: a connector cover;   a sensor in the device detecting the presence of the connector cover; and   the sensor having a signal controlling enabling and disabling of the termination impedance circuit, the signal causing the termination impedance circuit to be enabled when the sensor detects the presence of the connector cover.   
     
     
       2. The apparatus of claim 1; the connector cover further comprising a projection; and   the sensor detecting the presence of the projection.   
     
     
       3. The apparatus of claim 1; the connector cover further comprising a reflective surface; and   the sensor detecting the presence of the reflective surface.   
     
     
       4. The apparatus of claim 1, the connector cover further comprising a hinged edge, attaching the connector cover to the device. 
     
     
       5. The apparatus of claim 1 further comprising a tether attached to the device and to the connector cover. 
     
     
       6. A method for automatic termination of a computer bus by a peripheral device on the computer bus, the method comprising the following steps: (a) covering a connector on the peripheral device, by a cover, when the connector is not connected to the computer bus;   (b) detecting, by a sensor within the peripheral device, whether the cover is covering the connector; and   (c) enabling termination by a termination impedance circuit when the sensor detects that the cover is covering the connector.   
     
     
       7. The method of claim 6, step (b) further comprising detecting, by the sensor, a projection on the cover. 
     
     
       8. The method of claim 6, step (b) further comprising detecting, by the sensor, a reflective surface on the cover.